The present invention relates to the use of lymphotactin, a recently discovered chemokine, for therapeutic administration to animal or human patients. The administration of the chemokine will attract cytotoxic T lymphocytes (CTL) and/or Natural Killer (NK) cells. In addition, the biological effects of lymphotactin can provide many of the effects of MIP-1, e.g., protecting hematopoietic stem cells from the effects of cell cycling dependent treatments, including chemotherapies and radiation therapies which specifically target cycling cells. Lymphotactin also can attact class I MHC expressing cells, e.g., which are the mediators of tissue rejection.
The circulating component of the mammalian circulatory system comprises various cell types, including red and white blood cells of the erythroid and myeloid cell lineages. See, e.g., Rapaport (1987) Introduction to Hematology (2d ed.) Lippincott, Philadelphia, Pa.; Jandl (1987) Blood: Textbook of Hematology, Little, Brown and Co., Boston, Mass..; and Paul (ed.) (1993) Fundamental Immunology (3d ed.) Raven Press, New York.
For some time, it has been known that the mammalian immune response is based on a series of complex cellular interactions, called the xe2x80x9cimmune network.xe2x80x9d Recent research has provided new insights into the inner workings of this network. While it remains clear that much of the response does, in fact, revolve around the network-like interactions of lymphocytes, macrophages, granulocytes, and other cells, immunologists now generally hold the opinion that soluble proteins, known as lymphokines, cytokines, or monokines, play a critical role in controlling these cellular interactions. Thus, there is considerable interest in the isolation, characterization, and mechanisms of action of cell modulatory factors, an understanding of which should lead to significant advancements in the diagnosis and therapy of numerous medical abnormalities, e.g., immune system and other disorders.
Lymphokines apparently mediate cellular activities in a variety of ways. They have been shown to support the proliferation, growth, and differentiation of the pluripotential hematopoietic stem cells into vast numbers of progenitors comprising diverse cellular lineages making up a complex immune system. These interactions between the cellular components are necessary for a healthy immune response. These different cellular lineages often respond in a different manner when lymphokines are administered in conjunction with other agents.
The chemokines are a large and diverse superfamily of proteins generally considered a subset of the cytokines. The superfamily is subdivided into four branches, based upon whether the first two cysteines in the classical chemokine motif are adjacent (termed the xe2x80x9cCxe2x80x94Cxe2x80x9d branch) or spaced by an intervening residue (xe2x80x9cCxe2x80x94Xxe2x80x94Cxe2x80x9d), or a new branch which lacks two cysteines in the corresponding motif, represented by the chemokines known as lymphotactins. See, e.g., Schall and Bacon (1994) Current Opinion in Immunology 6:865-873; and Bacon and Schall (1996) Int. Arch. Allergy and Immunol. 109:97-109. A new fourth branch is represented by a new chemokine designated CX3C chemokine.
Many factors have been identified which influence the differentiation process of precursor cells, or regulate the physiology or migration properties of specific cell types. These observations indicate that other factors exist whose functions in immune function were heretofore unrecognized. These factors provide for biological activities whose spectra of effects may be distinct from known differentiation or activation factors. The absence of knowledge about the structural, biological, and physiological properties of the regulatory factors which regulate cell physiology in vivo prevents the modification of the effects of such factors. Thus, medical conditions where regulation of the development or physiology of relevant cells is required remains unmanageable.
This invention provides methods of increasing the numbers various lymphocytes, e.g., NK cells and cytotoxic T lymphocytes (CTL). The method comprises administering an amount of lymphotactin where said amount is effective to either attract cytotoxic T cells and/or NK cells, and/or to induce proliferation of resident cells. A preferred lymphotactin is human lymphotactin, though rat or mouse lymphotactin will function in their own, and biologically cross-reacting species. The preferred single dosage of lymphotactin is about 1 to 100 xcexcg/kg body weight. Alternatively the amount of lymphotactin administered in a single dose is about 10-800 xcexcg, or to reach a concentration of from pM to 1 xcexcM of patient sera.
Alternatively, an antagonist will be effective in preventing the recruitment of such cells. This may be important, e.g., in a transplantation context, where NK and/or CTL function is harmful.
This invention also provides methods of protecting hematopoietic stem cells. The method comprises administering an effective amount of lymphotactin where said amount is effective to inhibit hematopoietic stem cell sensitivity to a cell cycle dependent cytotoxic treatment, e.g., chemotherapy and/or radiation therapy. In certain embodiments, the lymphotactin is administered in combination with another active agent, e.g., another chemokine. Such chemokines may include, e.g., MIP-1xcex1, MIP-1xcex2, etc.
More particularly, the invention provides a method of increasing the numbers of NK and/or CTL cells at a location in an animal, comprising administering an amount of lymphotactin effective to increase said numbers. In preferred embodiments, the increasing is by recruitment of cells to that location; or the recruitment is to a tumor cell. Other preferred embodiments include where the tumor cell is from a solid tumor; where the increasing is by proliferation of the cells; where the increasing is of CTL cells; or where the animal is a rodent. Typically, the effective amount is between 20 and 800 xcexcg; or the administering is parenteral.
Also provided is a method of reducing allogeneic reaction from tissue transplant in an animal, comprising a step of administering an effective amount of an antagonist of lymphotactin to the animal. Typically, the antagonist comprises an antigen binding site from an antibody which neutralizes mouse lymphotactin; the antagonist is administered at a dose of about 1-10 mg/kg body weight; or at about 1 to about 100 xcexcg per milliliter of patient sera; or the tissue is an organ. In preferred embodiments, the antagonist reduces the influx of NK or CTL cells to the tissue; or the tissue is an organ transplant, or bone marrow transplant.
The present invention further provides a method of inducing cell cycle quiescence in a hematopoietic stem cell, comprising a step of administering to the stem cell an effective amount of lymphotactin. Preferably, the lymphotactin is a primate lympotactin; the quiescence imparts insensitivity to a cell cycle dependent cytotoxic treatment; or the treatment is a chemotherapy or radiation therapy.
Conversely, an antagonist will be effective in preventing the normal effect of natural lymphotactin, and may be useful in inducing specific hematopoietic stem cells to start cell cycling, and subsequent proliferation and/or development.